The voter turnout was very low.
It wasn't that so many people support Trump, but that Kamala was inedible considering her support for the mass murdering of Palestinians and the whole WW3 prospect.
If she had taken a tough stance against genocide and Netanyahu, I'm confident many more would've rallied to her side, although she also suffered from a lack of charisma and appearing fake at times. Tim Walz did most of the charisma heavy-lifting.